Most Tower Defense losses are decided before the third wave. If you spent your gold on a long line of cheap towers, you will leak on wave five and never recover. If you spent it on two good towers in the right places, the rest of the game plays itself.
Distance is damage
A tower earns its cost by how long enemies stay inside its range. A tower on a straight stretch covers a short window; a tower on the inside of a corner covers the same path twice. Before buying anything, walk the road and find the corners where the path doubles back on itself.
On most maps the best single spot is the inner corner nearest the spawn. Enemies spend the longest time there, and later waves stack up in that window.
Two towers beat four
A level-two tower is usually better value than two level-one towers: it costs less than a fresh tower plus the spot you would have used, and it concentrates damage where the path is already covered.
The opening that works on almost every map:
- Buy one arrow tower at the best corner.
- Upgrade it once before wave two.
- Add a second tower at the next corner, not next to the first.
- Only after two upgraded towers exist, start adding cannons.
Arrow versus cannon
Arrows are for single targets and lead the wave. Cannons are for clusters and pay off when enemies bunch up at a corner. Because wave composition shifts toward groups, the correct curve is: mostly arrows early, a cannon at each corner by wave four, upgrades on the arrows after that.
A cannon on a straight run is nearly wasted. Put it where the path bends so the splash hits the same group twice.
Upgrades are cheaper than map coverage
Every build spot you leave empty is gold you can put into a tower that already has a good position. Two highly upgraded towers at the two best corners will out-damage five level-one towers scattered along the road.
The exception is wave six onward: if a single tower is doing all the work, one stun or one fast enemy type ends the run. By then you want at least three towers with real damage.
Reading a leak before it happens
When a wave reaches the last third of the road with half its health left, you are already leaking. Do not wait for the lives to drop — sell nothing, but spend all remaining gold immediately on the tower nearest the exit. A weak tower at the exit is worth more than a perfect plan for next wave.
Waves seven and eight
The last two waves are damage checks. Before starting wave seven, make sure:
- Every corner has a tower with splash or a tower with high single-target damage.
- You have no unspent gold.
- Your three strongest towers are the ones closest to the final corner, not the ones closest to the spawn.
If you are short, upgrade the towers that already see the most traffic rather than building new ones in empty spots.
The one-line summary
Spend early on position, spend mid-game on upgrades, spend late on the exit. Gold left in the bank at wave eight is the most expensive mistake in the genre.
